Download pH notes

 What
does it stand for?
 Percent
Hydrogen ions (H+)
 Measures
the amount of H+ in a solution
 Goes from 0-14
• When H+ (hydrogen ion) and OH- (hydroxide ion) are
equal = neutral solution (pH 7)
• Above pH7 = Basic/Alkaline
• Below pH 7 = Acidic
 pH
scale is logarithmic
• pH 5 is 10 times more acidic than pH 6
• pH 4 is 100 times more acidic than pH 6
 Have

more H+ than OH-
( a compound that donates a H+)
 pH
below 7
 As acidity goes up, pH goes down
 Sour to the taste
 Sharp odor
HCl Stomach acid…eewwwww
Fruit juice…mmmm
 Have

more OH- than H+
(compound that accepts a proton)
 pH
above 7
 Bitter to the taste
 Slippery to the touch
 Usually found in household cleaners—
bleach, soap, Drano
 Substance
that resists pH changes when
an acid or base is added
 Important
for maintaining constant pH
levels in organisms
 able
to neutralize small amounts of added acid
or base, to maintaining the pH of the solution
relatively stable.
 Buffer
solutions have a working pH
range/capacity which determine how much
acid/base can be neutralized before pH
changes, and the amount by which it will
change.
A
buffer is able to resist pH change
because the two components (conjugate
acid and conjugate base) are both
present and are able to neutralize small
amounts of other acids and bases when
the are added to the solution.
 We
are made of 70%+ water
 Water
is a combination of H+ and OH-
 In
any water sample, some molecules are
coming apart into H+ and OH-, called
ionization or disassociation
• Mostly H-O-H
• Some H+ and some OH- (equal amounts)
 Living
cells must maintain a stable level
of H+ and OH- within narrow limits in
order to survive!
 pH
influences important reactions in the
body
 Every
reaction in a living system is
dependent (to some extent) on pH
 Examples:
• Marine life cannot live in solutions with a pH less
than 7.8-8.6
• Some fungi and bacteria only grow in acidic
environment
• Urine has a pH of 6.0
• Human blood has a pH of 7.4
 Salivary
= amylase 6.7-7.0
 Esophagus
 Stomach = pH 1-3 ACID
 Hydrochloric Acid, Pepsinogen,

mucus
 Small
intestine = pH 7-9 BASIC
• Duodenum
• Ileum/jejunm
 Large
Intestine = pH 5.5-7 BASIC
• Ascending, transverse, descending colon